Turn skillet to medium-low
Add butter to the skillet
Add cut-up red onion and 1 tablespoon of garlic to the skillet
Sauté red onion and garlic for 1 minute
Increase heat of skillet to medium
Add the bottoms, stalks, of asparagus to the skillet
Sauté all together for 3 minutes
Add the tops, spears, of asparagus to the skillet
Cook all together for 1 minute